WILMINGTON, Delaware—The US Food and Drug Administration has granted approval to AstraZeneca’s breast cancer drug Faslodex (fulvestrant) Injection for treatment of hormone-receptor-positive metastatic breast cancer in postmenopausal women with disease progression following antiestrogen therapy, such as tamoxifen(Drug information on tamoxifen) (Nolvadex). Faslodex is a selective estrogen-receptor antagonist without known agonist effects.
Faslodex works by binding to, blocking, and degrading the estrogen receptor, AstraZeneca said in a news release announcing the approval. It is given as a monthly intramuscular injection, which may assist health care professionals in monitoring compliance and may also make treatment more convenient for some patients, the company said.
The FDA approval was based on data from two phase III, randomized multicenter, studies (one in North America and one predominantly in Europe) comparing Faslodex 250-mg once-monthly injection with daily 1 mg oral administration of the aromatase inhibitor anastrozole(Drug information on anastrozole) (Arimidex).
The 851 women in the trials were postmenopausal with a variety of involved sites, including liver and lung, and had been treated with one prior hormonal therapy, in almost all cases, tamoxifen.
Objective response rates in the North American trial were 17% with Faslodex vs 17% with anastrozole, and in the European trial 20% with Faslodex vs 15% with anastrozole. The time to progression for Faslodex vs anastrozole was 5.5 months vs 3.5 months in the North American trial, and 5.5 months vs 5.2 months in the European trial.
